About 25 million people in Bangladesh, nearly 20 percent of the country’s population, are at risk of injury or death from arsenic in their drinking water, according to the United Nations Children’s Fund. UNICEF is working to raise awareness of the problem and encourage water filtering and collection of rainwater for drinking. In the past, the group has defended itself against claims that its policy of encouraging well-drilling exacerbated the poisoning problem. Arsenic occurs naturally in rocks and sediments in the country.